1. Field of Invention
This invention relates generally to insulating disposable cups and containers, specifically to insulating wrappers, methods for producing insulating wrappers, and methods for making insulated containers with insulating wrappers.
2. Prior Art
Many types of cups and containers are available, each with a specific set of characteristics relating to print quality, rigidity, insulation, biodegradability, recyclability, clarity, permeability, microwavability, and shelf life, among other characteristics. Many types of cups have desirable features and benefits in one or more areas, but undesirable features in other areas.
E.g., cups made from expanded polystyrene (EPS), well known in the art, are excellent thermal insulators and maintain the temperature of a drink, whether hot or cold, for a long period of time. They also provide a barrier between the hot or cold temperature of the product and the user's hand. However EPS cups are generally considered environmentally unfriendly because they are not biodegradable. As a result, their use has been banned in some municipalities. Also, in order to print EPS cups a slow and costly off-line printing process must be used because the cups must be printed after they have been formed, and their relatively rough surface does not permit high-resolution printing.
Standard single-wall paper containers, also well known in the art, are generally considered to be more environmentally friendly than EPS cups, but they have poor insulating qualities. As such, many coffee shops resort to double cupping, which is the practice of serving a hot beverage in two stacked single-wall paper cups in order to provide some level of insulation. This is a very expensive and wasteful. Alternatively, designers have provided a number of cup sleeves which are wrapped around a single wall paper cup to provide insulation to keep drinks hot and hands comfortable; see, e.g., U.S. Pat. No. 5,205,473 to Coffin (1993), U.S. Pat. No. 5,794,843 to Sanchez (1998), and U.S. Pat. No. 6,277,454 to Neale et al (2001). One of the shortcomings of cup sleeves is that they must be assembled and/or placed onto the cup when the beverage is served. This requires extra labor and slows the speed of service. Also the need for cups and sleeves require additional and simultaneous purchasing, additional storage space, and additional inventory management. Cup sleeves also have a tendency to fall off of the cups, do not conveniently fit in all vehicle cup holders, and cover the graphics printed on the cup.
Single-wall plastic cups made from materials such as polyethylene terephthalate (PET), polystyrene (sometimes called PETE), (PS), polypropylene (PP), and high density polyethylene (HDPE) are well known in the art, and are formed through either thermoforming or injection molding processes. Plastic cups are aesthetically pleasing and can be made with high barrier properties to offer longer shelf life to the products that they contain. A barrier material called EVOH (Ethylene Vinyl Alcohol Polymer) can also be added to provide a better oxygen barrier. A cup made from a thick layer of HDPE will provide a significant moisture barrier. Plastic cups made with both HDPE and EVOH are resistant to both moisture and oxygen to provide extended shelf life to the products they contain. Some types of plastic cups, such as those made from polypropylene, are resistant to high levels of heat and as such are microwavable. Also, plastic cups do not have a seam area, which makes them relatively leak proof. However plastic cups must be printed off-line after the cup is formed, which is an expensive process and limits the graphic capabilities. Another problem is that these cups are poor thermal insulators. They will loose their heat or cool very quickly, and are uncomfortable to carry when holding hot or cold contents. Another deficiency is that their sidewall rigidity strength is poor.
Multi-layered paper cups have been designed to provide thermal insulation and increased strength. U.S. Pat. No. 3,908,523 to Shikaya (1975), U.S. Pat. No. 5,205,473 to Coffin (1993), U.S. Pat. No. 5,547,124 to Mueller (1996), U.S. Pat. No. 5,685,480 Choi (1997), U.S. Pat. No. 5,769,311 Morita et al. (1998), U.S. Pat. No. 5,775,577 Titus (1998), U.S. Pat. No. 6,039,682 Dees et al. (2000) and U.S. Pat. No. 6,253,995 Blok et al. (2001) all show multilayered cups with at least three layers, which include some form of an inner cup made from paper and an outer cover or wrapper to provide insulation. The wrapper comprises a multi-ply sheet consisting of at least one base sheet, and at least one corrugated or embossed sheet adhered to the base sheet. Although thermally insulated and strong, these cups are expensive to manufacture because the corrugated or embossed sheet must be adhered to cover the entire surface of the base sheet through a lamination process. This is a process whereby adhesive, such as hot melt or heated polyethylene, or a paste adhesive such as a starch based cold glue, is applied either to the surface of the embossed sheet and/or the base sheet and the two sheets are pressed together forming a multi-ply insulating sheet. The wrapper is then cut out (a process called blanking) of this multi-ply sheet and wrapped around and adhered to an inner cup. The process of laminating the sheets together is expensive and wasteful. There is a significant amount of value-added multi-ply sheet trim scrap which is wasted when blanking the wrapper. There is also a significant amount of adhesive used to secure the embossed sheet across the entire surface of the base sheet, which is typically done along all of the tips of the corrugations or embossments. The printing process is expensive because either the base sheet must be printed prior to laminating, which causes significant registration and distortion issues after the sheets are laminated together, or the multi-ply sheet is printed after the sheets are laminated, which is difficult because of the thickness and stiffness of the multiply sheet and the excess compressibility of the sheet. In any event, it is very difficult to offer high quality printing at a cost effective price on these types of insulated cups. Finally it is difficult to wrap or bend the multi-ply laminated wrapper around an inner cup because of the limited flexibility of thick laminated paperboard.
The insulated cups of U.S. Pat. No. 5,660,326 to Varano and Sadlier (the present inventor) (1997), and U.S. Pat. No. 6,085,970 to Sadlier (2000) have overcome these deficiencies. These cups have gained widespread acceptance in the market and many millions have been sold throughout the world. Although the cups of these two patents are major improvements, I have discovered that both the cups and their manufacturing processes can be improved even further. Since the inner cup and the outer layer are made from a continuous blank, these two parts are made from the same material. This is disadvantageous since the inner layer must be made from expensive polyethylene coated board for waterproofing and thus the outer layer must also be made from this same expensive material. Also, since the inner and outer layers are made from the same blank, the entire blank, rather than just the outer portion of the blank, must be passed through a printing press, which is a relatively expensive processing operation. The sidewall blank must also be folded in order to form the inner and outer layers of the cup from the same elongated blank. The process of folding the blank is an expensive additional step which requires precise registration.